1. Field of the Invention
The present invention relates to a distribution apparatus and a quench zone mixing apparatus (or device) that may include the distribution apparatus, both of which are suitable for efficiently mixing and redistributing reactants across the horizontal cross-section of a vertical reaction vessel.
2. Discussion of Related Art
Many catalytic processes are carried out in reactors that contain a series of separated catalytic beds. Frequently, in such processes, quench zone mixing devices are advantageously located to provide rapid and efficient mixing of the fluid streams being processed in the reactor with a cooler fluid stream supplied from an external source. Consequently, the temperature of the process stream entering the successive catalyst beds can be controlled. One skilled in the art will appreciate that the better the mixing of the reactant streams, the better the temperature and reaction can be controlled. As a result, the overall performance of the reactor will be better.
Examples of quench zone mixing devices include U.S. Pat. No. 3,353,924, U.S. Pat. No. 3,480,407, U.S. Pat. No. 3,541,000, U.S. Pat. No. 4,669,890, and U.S. Pat. No. 5,152,967. Some of these devices are complicated and are prone to plugging. Others need a relatively large vertical space to ensure the desired degree of mixing. Still others create an undesirably high pressure drop. Consequently, there is a continuing need for a suitable quench zone mixing device that can efficiently mix fluid streams in a low vertical space with an acceptably low pressure drop.
Typically, the quench zone mixing devices are located above an associated fluid distribution system; for example, a horizontally disposed distribution plate or tray. The distribution plate collects the fluid (vapor and liquid), uniformly distributes it across the plate and discharges the fluid on to the catalyst bed. Such distribution tray may contain a number of “bubble cap” assemblies which may be disposed over one or more openings in the distribution tray. The bubble cap provides intimate mixing of the vapor and liquid before the mixed phase fluid is distributed across the catalyst bed.
Examples of distribution trays include U.S. Pat. No. 2,778,621, U.S. Pat. No. 3,218,249, U.S. Pat. No. 4,960,571, U.S. Pat. No. 4,836,989, U.S. Pat. No. 5,045,247, U.S. Pat. No. 5,158,714 and U.S. Pat. No. 5,403,561. Although one or more of these designs may be acceptable, there is still room for improvement, particularly in providing a uniform distribution of vapor and liquid phases into contact with the catalyst in the reactor vessel.